Autosomal dominant polycystic kidney disease (ADPKD) is a common genetic disorder that affects 1/1000 persons, often leading to significant morbidity from renal failure or stroke. Previous positional cloning efforts have defined a genetic interval of less than 500 kilobases containing the PKD1 gene and identified 23 cDNAs from the region; the long-term aim of this proposal is to pinpoint and study the gene and mutations that cause PKD1. Initially, trinucleotide repeats from the interval will be analyzed for disease-related expansions, which have been shown to cause disorders clinically similar to ADPKD. All new polymorphic markers will be used in linkage studies. Loci amplified by the polymerase chain reaction will be examined in cyst-derived tissues for loss of heterozygozity. If the gene is not identified by studying unstable elements, the strategy will employ systematic methods such as single- stranded conformation polymorphism analysis (SSCP) to scan regional transcripts for mutations. Analysis of the PKD1 gene sequence, genomic structure, and expression pattern will be performed. Phenotypic correlations of mutations will be investigated. The second phase of the project will depend on the nature of the gene and predicted gene product. Experiments are contemplated to develop antibodies to study the spatial and temporal distribution of the gene product. In addition, the project contemplates the development or confirmation of in vitro and in vivo models of polycystic kidney disease abnormalities.